Spark plug extension



FIG. 1 is a perspective view of the spark plug extension;

FIG. 2 is a front view thereof;

FIG. 3 is a back view thereof;

FIG. 4 is a left view thereof.

FIG. 5 is a right view thereof.

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof.

The broken line portion of the figure drawings is included to show unclaimed subject matter only and forms no part of the claimed design. 

CLAIM We claim the ornamental design for a spark plug extension, as shown and described. 